bug in pgtk rendering

[Andrew Cohen]

I have noticed a persistent rendering bug with pgtk which seems to be
related to multiple monitor use. I am using 2 monitors (primary
3840x2160 at 200% scaling with gnome; secondary 1920x1080 at 100%
scaling). I don't see problems on the primary monitor. But
intermittently on the secondary monitor I see large portions of the
screen with blocky blurred text:

It comes and goes---re-exposing the window sometimes fixes it, as does
moving the frame to the primary monitor and back; but the distortion
always returns.

I'm happy to do some debugging but don't know exactly where to start. 


-- 
Andrew Cohen